National differences in abdominal aortic aneurysms treatment reported

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A new report that documents the demographics, treatment modes and outcomes of more than 84,000 patients from 386 hospitals, in ten countries who underwent treatment for abdominal aortic aneurysms (AAAs) or carotid reconstruction, will be released at this year’s European Society for Vascular Surgery (ESVS) meeting in Nice, France.

The ‘Second Annual Vascunet Database Report 2008’ includes comparisons of national outcomes for AAAs, and it is hoped the report will be used to detect national differences in the presentation and treatment of AAAs and identify changes over time.

Mr Chris Gibbons, Morriston Hospital, Swansea, UK, and Chairman of the ESVS Vascunet Committee, commented: “By amalgamating the data from the registries, we are provided with outcome data that allow us to identify risk factors, identify possible differences and ultimately, improve outcomes. More importantly from the surgeon’s standpoint, it has established benchmarks against which we can compare our outcomes.”

 

Data submission and limitations

The data contained in the report, published by Dendrite Clinical Systems on behalf of the ESVS, were collected over a 14-year period (1994–2007) for Sweden, a 13-year period (1994–2006) for the UK and New Zealand, 12 years for Denmark (1996–2007) and eight years for the State of Victoria, Australia (1999–2007). In addition Finland, Italy and Hungary submitted five years data (2003–2007), Norway three years data (2003–2006) and Switzerland two years of data (2005–2006). There are some limitations to the report concerning validation and differences between the data fields of the registries, but despite this some important conclusions can be drawn from the report.

“In order to improve the validity of comparisons and ensure contemporary data, we have restricted the analysis to the last five years,” commented Gibbons. “Whilst, as before, there are discrepancies in the data definitions and the degree of validation between the various national registries, some general conclusions can be legitimately drawn from the data. Some of the analyses have provided further support to the conclusions of certain randomised clinical trials and revealed some surprising national differences in outcome that deserve further investigation.”

 

Key AAA findings

The report revealed some interesting differences in the demographics between the countries. For example, Australia had the highest average age at the time of AAA operation (73.7), whereas Hungary has the lowest (67.4). In addition, the report also reveals interesting differences in the percentage of women undergoing AAA repair varying between countries from 8% in Italy to 21% in New Zealand.

Of the total cases reported, 21% of patients with AAA presented with rupture. Again, there were some interesting comparisons to be made between the countries, with ruptures totaling 38% of cases in Finland but only 12% in Hungary. The report also highlighted possible differences in the incidence of hypertension, respiratory disease, renal disease and smoking.

 

Mortality

The overall mortality of AAA repair was 9.5%, with the mortality of surgery 2.8% for intact aneurysms and 33% for ruptured aneurysms. Most registries included both open and endovascular aneurysm repair (EVAR), however EVAR was not recorded in Finland and only partially captured in the UK. Nevertheless, it is reported that the overall mortality for surgery for intact aneurysms was 3% and was significantly less for EVAR than open repair (1% versus 4%), confirming the results of the EndoVascular Aneurysm Repair (EVAR) 1 trial. There was a surprising variation in mortality in the repair of intact aneurysms ranging from 1.6 % in Italy to 7.2% in the UK, which reflected differences in the outcome of open repair. This merits further study.

As expected, those undergoing elective EVAR had shorter lengths of stay (5.9 versus 10.8 days) than those undergoing open repair. The UK had the longest length of stay (14.1 days), whereas Italy had the shortest (eight days).

 

Carotid data

For the first time, carotid reconstruction data from over 48,000 patients was included in the report. The data revealed that the mean age for carotid reconstruction was 70.8 years and was slightly greater for men (70.6 years) than women (71.2 years). The method of carotid endarterectomy was recorded by seven countries (15,735 patients), with eversion endarterectomy used in 34% of procedures, standard endarterectomy with patch in 39% of procedures and without patch in 26% of procedures. The surgical method was found to be country dependent with eversion endarterectomy used in over 90% of procedures in Hungary, but not used at all in Finland and Norway. Patches were preferred in Australia, New Zealand, UK and Finland but not in Sweden and Norway. In total, four countries recorded the type of anaesthesia, with general anaesthesia used in about 73% of cases in Australia and Italy, 50% in UK and 36% in Denmark.

The mortality rate for carotid endarterectomy was .45% and was unaffected by the endarterectomy method or type of anaesthesia. The mortality of carotid stenting was not significantly different from carotid endarterectomy (.39%). Mortality ranged from about 1% in the UK, Sweden and Denmark to less than .5% in Finland, Hungary, Italy and Norway. The peri-operative stroke rate was 1.4% for carotid endarterectomy vs. 2.1% for carotid stenting. This difference was statistically significant (p<.0001) and is of particular interest regarding the morbidity of carotid stenting and the differing results of the various randomised clinical trials comparing carotid endarterectomy and stenting.

 

Conclusions

The second Vascunet database report has combined the data from the registries of ten countries to form one of the largest vascular registries to date.

The findings have confirmed the results of randomised clinical trials (EVAR 1) showing the reduction in mortality of aortic aneurysm repair by using EVAR and confirmed that advancing age, cardiovascular, renal and respiratory disease are all important risk factors for surgical mortality.

For carotid surgery there was no difference in mortality between endarterectomy and stenting, but stenting seemed to be associated with a slightly higher stroke rate. Neither the endarterectomy method nor the type of anaesthesia appeared to influence morbidity or mortality to a significant degree

It is hoped that the next Vascunet report will see further registry information added and provide much needed data. “Many of these results are thought-provoking, and merit further focused research efforts. As more data is added and additional countries submit data, we will be able to produce more comprehensive reports. Hopefully in the future we could include other countries such as Spain, France, Germany, Holland and Portugal,” added Gibbons. “Whilst the Vascunet database is still in the development phase, it has shown the usefulness of international audit and it is hoped that this will expand both geographically and in the scope of the audit in years to come.”

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